A typical EAS system in a retail setting may comprise a monitoring system and at least one security tag or marker attached to an article to be protected from unauthorized removal. The monitoring system establishes a surveillance zone in which the presence of security tags and/or markers can be detected. The surveillance zone is usually established at an access point for the controlled area (e.g., adjacent to a retail store entrance and/or exit). If an article enters the surveillance zone with an active security tag and/or marker, then an alarm may be triggered to indicate possible unauthorized removal thereof from the controlled area. In contrast, if an article is authorized for removal from the controlled area, then the security tag and/or marker thereof can be deactivated and/or detached therefrom. Consequently, the article can be carried through the surveillance zone without being detected by the monitoring system and/or without triggering the alarm.
The security tag or marker generally consists of a housing. The housing is made of a low cost plastic material, such as polystyrene. The housing is typically manufactured with a drawn cavity in the form of a rectangle. A bias magnet is disposed within the housing adjacent to one or more magnetoelastic resonator. The bias magnet is made of a semi-hard magnetic material. The resonator(s) is(are) made of a soft magnetic material in the form of an elongate thin ribbon produced by rapid quenching. During operation, the security tag or marker produces a resonant signal with a particular amplitude that is detectable by the monitoring system. Notably, markers with a single resonator have about 65% of the amplitude of markers with two resonators. As such, single resonator markers have reduced system performance as compared to dual resonator markers.
There is a desire to reduce the width and/or thickness of the markers, and reduce the amount of resonator and bias materials used. Reducing the resonator width and/or thickness results in proportionally less output and reduced system performance.